1. Field of the Invention
The present invention relates to an electronic component installation device and method for manufacturing an electronic circuit substrate by installing a large number of parts such as electronic components on a circuit substrate.
2. Description of Related Art
FIG. 13 shows one example of an electronic component installation device. A mounting head 1 mounted on an XY robot 7 is constructed such that it is capable of picking up an electronic component 10 supplied from a parts tray 8 or parts cassette 6 with a suction nozzle 9 and placing it on a circuit substrate 15. Such electronic component installing actions are controlled by a controller 13 according to a prescribed installation program.
In FIG. 13, when the circuit substrate 15 is carried in and positioned at a prescribed location, the mounting head 1, which is capable of freely moving in X- and Y-directions by the function of the XY robot 7, picks up the electronic component 10 from the parts cassette 6 or parts tray 8 and moves to a point above a recognition camera 11 where the attitude of the electronic component 10 is recognized. Based on the recognition results, the attitude of the electronic component is corrected, after which it is installed on the circuit substrate 15 at a predetermined location. These actions are repeated until all of the electronic components needed for one circuit substrate are installed, and the circuit substrate which has been installed with all necessary parts is taken out, while a new circuit substrate is carried in for another cycle of installing operation repeating the above actions.
There are various kinds of electronic components 10 to be installed with the mounting head, and accordingly the thickness or height of the electronic components in a installing direction is diversified. Thus, when placing electronic components on the circuit substrate 15 with the mounting head 1, the distance the suction nozzle 9 descends towards the circuit substrate 15 needs to be varied in accordance with the height of the electronic component in the installing direction. This amount of downward movement of the suction nozzle 9 is normally determined as described below. The thickness of each of the electronic components is preliminarily measured using a slide caliper or the like, and component data is prepared based on this measurement in which thickness is determined with respect to each type of electronic components. This component data is used in an installation program for controlling actions of the mounting head 1. The mounting head 1 is controlled such as to lower the suction nozzle 9 a distance corresponding to the thickness of each of the electronic components stored in the component data when placing it on the circuit substrate 15.
However, with increasing employment of a large-scale integrated circuit or an odd-shape outer package in response to demands for more complex electronic circuits and for higher mounting density, electronic components of recent years, especially those which include very narrowly pitched leads or fragile packages, require more delicate handling. It is thus essential to avoid exerting a load on electronic components greater than necessary when placing them on the circuit substrate. In other words, the amount of descending movement of the suction nozzle effected by the mounting head must be precisely controlled.
However, in the information regarding dimensions of electronic components particularly in the thickness direction in the above mentioned component data based on which the descending amount of the suction nozzle is controlled, measurement errors or errors in dimensions of the electronic components are inevitably included. Especially when installing electronic components with minute leads or any other type of fragile components, such errors may well lead to mounting failures or cause damages to these electronic components.